Imaging with a Coronado PST

[Bassnut]

I know next to nothing about Solar imaging.
Im chuffed with my new PST, id like to image with it.
Ive searched IIS and find quite a bit of info on solar imaging, PST and suitable cams.
So, Im thinking a DSLR (or an ST10?), some pics ive seen are quite good or a DMK31, nice res and still get 30fps. I understand the 41 is a bit slow (fps), and I think the 21 is fast but a bit low res. Cant see colour version is of much use with the sun or moon, but then would be handy for planetary (although for that the lower QE would count I guess). I dont see a filterwheel for mono DMKs, so thats a bother. Is a colour DMK any disadvantage for sun or moon?, or should I stick with mono, even just for sun and moon only?.

Ive seen the backfocus issue, ill get round that.

Im not keen to spend huge amounts of readys yet (but forget webbies), all I want to start with is this (http://www.atscope.com.au/BRO/gallery114.html) kind of result Peter Ward also did with cheap gear.

[scagman]

Hi Fred,

Congrates on the PST.

That image was taken with equimpent I would cosider not so cheap. The camera is around $2700US and I would think the scope would be worth that too.

But yes I agree it would be nice to get images like that one

[Bassnut]

Well, I was kidding a bit. His Ha filter alone is something north of $4k, and the scope..........well a bit more than 10x that again :P.

[scagman]

WOW:eyepop:
In that case I would actually call that a lot more than no so cheap.:D

[Merlin66]

I'm more than happy with the results from the DMK41.
I use 1/120s exposures for the surface an 1/20 to 1/11s for proms.
The frame rate is not really an issue.
As we are working in monochromatic Ha light - a colour camera is totally unecessary and gives poorer results.

[Bassnut]

Excellent.mono 41 it is then. Thanks

[Peter Ward]

I would have gone for a Lunt 60...but happily recognise the PST's afforability.

Best bang for buck? Pressure tuned Lunt 80 without a doubt.

Cameras? SkyNyx works, but costs. The flea 3's look cool....

For sure a mono camera is the way to go.

[CapturingTheNight]

Hi Fred,

I just ordered the PST as well, and am anxiously awaiting its arrival. I'm going to try imaging as well. I thought you might be interested in these pics done with a PST by a friend of mine on an art site I'm a member of. First one is done with a DMK41 http://kevlewis.deviantart.com/art/Solar-activity-in-H-a-140811-252821416 and the next with a Canon 7D http://kevlewis.deviantart.com/art/Solar-Disk-100711-217659907.

[AndrewJ]

Are you wimping out and going widefield Fred????

Andrew

PS Agree with Peter, the Lunt80 pressure tuned scope
is an absolute corker for the price.

[iceman]

Go Fred!
I've got a PST too and plan to do more imaging with it, with the DMK41.

I haven't put my DSLR up to it yet but I guess that would work too if it fits the whole disc and comes to focus.

I need to get some practise in before the Venus transit and solar eclipse!

[Barrykgerdes]

Hi
There have been some interesting comments on solar imaging with a PST but how many have actually tried it.

I have a PST and they are great as an entry telescope for solar viewing and with a suitable eyepiece much can be seen.

However imaging is a different problem. The first thing needed is to mount the PST on a stable platform that can track the sun. The sun moves accross the sky at its solar rate not sidereal so your tracking rate needs to be set to this. As exposures are going to be short the movement during exposure won't be noticed and guiding not necessary but for multiple exposures and mosaics you will need to keep the sun in the picture.

The next problem is the camera to be used. I tried my basic set up with an LPI. Why because it was available. The big problem now was the laptop that I was using. Have you ever tried to use a laptop in bright sunlight while you try to manually focus and frame. Even with a shielded enclosure it was still near impossilble to do this accurately.

Have you ever tried to do a two star alignment or a polar alignment on a mount during daylight. My mount does not track the sun (autostar controlled), it won't even let you look at the sun so I needed to write a little program to make it track the sun. This needed a second computer. My polar alignment was only within about two degrees.

By the time I had got a prominence tuned and in focus I managed about three frames before the clouds rolled in. I haven't tried again since

When I get another chance to do some imaging I will need to have solved all the above problems. (and get the PST back from my grandson who does not want to part with it).

Barry

[Merlin66]

I used the PST mounted on a basic single RA drive EQ2
A small dovetail held the PST, rough "polar" alignment and a bit of "fine" tuning using the drift of the suns image.
Std sidereal tracking rate
Worked 100%
Now I have a HEQ5pro set up for solar with a dual bar, so I can have either the double stack SM60, 88mm modded PST or the SM60/PST double stack alongside a 100 f5 Baader white light scope.
I use a small table, 60 litre grey plastic tub, with the lid hinged with gaffa tape to hold the laptop and an ol' dark sheet thrown over to keep out the light.
Worked well for the last five years.
(The attached image shows the double stcked SM60 on the ED80/EQ2 and the Vegemite controller)
HTH

[iceman]

Barry some of those are not really big issues.

The PST has the solar finder built in. I know where the Sun is, I don't need GOTO to make my mount find it for me so I don't need any 2-star alignment.

Even sidereal rate is close enough for tracking the sun, especially at the short focal lengths normally used for solar imaging. The hand controller satisfies the need to re-center.

[Barrykgerdes]

Hi Mike
Wait till you try it.

For visual use finding, focusing, tuning and tracking the sun is no bother.

I thought the same as you till I tried it. You can't keep the sun in view manually and photograph it at the same time. You don't need a goto but you do need to track automatically.

I got out my old autostar mount and made adaptors for the PST. Did a fake alignment that would have been good enough to track the stars but it was no good for the sun that slipped out of view in a couple of minutes. That is why I needed to write a tracking program. I could not see the computer screen in the daylight so I next had to build a shielded enclosure.

My original aim was to take a series of time lapsed shots and make a movie of the prominences. I never got that far before I had to pack up after spending about 3 hours getting around the basic problems.

So if you want to take serious photos you will need to align your mount and track the Sun

Barry

[Barrykgerdes]

Further to my progress

I now have a HEQ5 pro and a program to track the sun and a much better shielded enclosure so my next attempt will be a little more sophisticated. My point is that the PST is a nice little scope for solar viewing but if you want "professional" results you need a "professional approach"

Barry

[Poita]

My current Mac laptop is bright enough in full sun thankfully, my old one certainly wasn't!

Do any of the laptop based guiding programs allow the EQ6 to track the sun correctly?

[Barrykgerdes]

The Synscan and EQMOD drives do have access to controlling the track rate but I have not tried it yet.

Barry

[Merlin66]

On the HEQ and NEQ mounts controlled by the Synscan handcontroller (V3) you can select "Solar" rate tracking.....

I don't find it difficult to keep the solar image well within the frame of a DMK21 or DMK41 for 20 minutes or so......

[Paul Haese]

Perhaps I ought to dispell a few things being said here.

I have imaged with the PST years ago before I got my solarmax60.

You can image easily with this little scope. You need to cut down the nose cone of the adapter on a monochrome camera. Forget using a DSLR. This is monochrome light so monochrome imaging gives sharp results. The bayer matrix on a DSLR will kill the image for detail. Besides the camera will weight too much and rotate.

Next using a blanket or towel over a box is great for seeing the image on the Laptop screen. I do this everytime I image and it is no drama.

Like Mike said sidereal is fine for imaging and you have to be a long way out of PA for the image to drift quickly. I use solar rate myself but it can be done with a quick setdown and using a compass to find PA.

You don't need to do a 2 star alignment. Nearly every mount has a free tracking rate that does not require an alignment. Just set it down and get it tracking.

As for images here (http://paulhaese.net/AR933%2014%20Jan%202006.html)is one. And anothe (http://paulhaese.net/AR930.html)r and another (http://paulhaese.net/AR930.html). Each were taken with a 2.5x barlow which easily reached focus. Just make sure you can reach the etalon and the focusor and you can have your head under the blanket.

Fred if you want to know more just ask me.

[Bassnut]

Peter. Yes, well all the stuff you mention ive looked at, all very good ofcourse, but all a bit pricey at this stage. Ill see if im any good at it 1st with lesser gear.

Greg. Those links look promising, it looks like a DSLR is certainly an option.

Andrew. mmmm, it is a bit WW isnt it. Still, its a different sort of experience, so I hope to get away with it without loosing what little credibility I have ;-).

Mike. If youve got a DMK41 too, then thatll extra do me. Eclipses sound like fun with it all too.

Barry. Youve bought up some interesting topics there. Ive been wondering how to track the sun. I dont even know if the PME has a solar rate. Perhaps I can roughly guide on it with a filter on the guide scope at sidereal . Ill see if I can set the speed on my Timemachine to track the sun on an EQ3. Yes, a lappy in full sun isnt flash.

[Bassnut]

oops, some post crossover there, much to read

[Bassnut]

Excellent :thumbsup:

[Barrykgerdes]

I think everyone has missed my message to beginners.

Don't expect to plonk your PST down on a non tracking mount with a CCD and a computer and take pictures of the Sun. You need to spend quite a bit of time in preparation the first time otherwise you will spend all day chasing your tail.

Barry

[Barrykgerdes]

Oh and especially for Fred

With your normal attention to mechanics and detail and experience in narrow band I will be expecting to see some really first class images of the sun at the next meeting.

Barry

[AndrewJ]

Gday Baz



Yep, both AltAz and Polar
With my EQ6, i plonk it down, just hit enter on date time etc ( without changing anything ). Then i go to the Hbx and set tracking rate to solar.
Then i manually slew to centre the sun and let it track.
With my Meades, i set up altaz ( with Nth and level eyeballed ) and do a manual one star align.
Then i select my asteroid ( ref below ) and hit goto.
Then i just manually centre the sun and let it track.
No PC reqd
( you could also just enter the RA/DEC for the sun into the hbx
and do a manual goto, or manually slew all the way if reqd )



So cheat :-)



There is a standard asteroid developed for the Meades that is basically an "Anti Earth". As such, when you issue a "goto", the blasted sun is always in the way :-) This gets you close
Whilst the Meades will not then "track" to account for DEC errors
you can easily get 30mins or more using a rough alignment.
Also, if you apply Richard Seymours tracking rate patch to your Hbx,
you can manually adjust the tracking rate in increments of .01 of sidereal
to get a better RA rate.

Andrew

[Barrykgerdes]

Now come on Andrew

Both you and I know how to get around all the drawbacks. Yes I have done two star and polar alignments during daylight. But does the average beginner know all the tricks we can use or have. I was only using an old DS2014(?) mount and made up some brackets to hold the PST in the hope that it would drive the scope in some sort of a tracking mode while I took a few photos. However the short cuts were not good enough. The tripod was not stable and I could not see the laptop (that's where I needed to focus the image). I needed to make a better setup and time ran out.

Actually I did not need to write a program. I already had one that just needed to be set up on another computer.

Next time I will be better set up. I will use the HEQ5 It has a solar track rate and I will have it polar aligned before I start. I will have the laptop where I can see it and a better monochrome CCD.

Barry

[Paul Haese]

Looks like you missed mine Fred.:)

[Bassnut]

If you mean yr post, I did see it, thanks for the info, "double stacking" looks interesting and the pics look great, thats the kind of pics im after :thumbsup:.

[Merlin66]

Fred,
I attach a Solar image taken with a PST, x2.5 TV Powermate and a DMK41 camera.
This was taken by "Photobykev" 16th Aug, and posted on the UK SGL site.
Kev only started solar imaging about a month ago, initially with a DSLR then changed to a DMK41.
Building the mosaic still has work to be done, but it shows what can be achieved with the basic PST. Excellent work.
He used the PixInsight "Dynamic Background Extraction" (DBE) on some early whole disk images to remove the "hot spot" - looked very promising.
HTH

[Bassnut]

Yes, I like the look of that. Interesting the use of a powermate and then mosaicing, food for thought. Would a powermate negate the need for cutting down the tube to get BF do you think?.

[Merlin66]

Yes.
The powermate can just be dropped into the PST and the camera with a normal nosepiece used.
I actually use the TV T thread adaptor for the powermates which reduces the "overhang" and a T thread to C thread adaptor to the DMK.
HTH

[sheeny]

The other trick to try, Fred, if you're reluctant to cut the nose piece is a barlow lens. Unscrew the lens from the barlow and screw it in the front of the nosepiece.:thumbsup: It doesn't increase magnification a lot but it might just get you in focus (depending on the length and shape of the nosepiece of course;)). It worked for me before I bought a second nosepiece and modded one specifically.

Al.

[multiweb]

Can we expect 2"x2" prominence close-ups? I wanna see SOHO. :P

[AndrewJ]

Gday Baz



I can only get around "most" at present :-)
Some still have me baffled.

My reply was also intended to provide the average beginner with some ideas on what can be done. Its amazing how many people pickup tidbits whilst lurking.

Andrew